Resolve relative paths in command names for complete -p

Fixes #6001

CHANGELOG.rst

@@ -69,6 +69,7 @@ Completions
   - ``firewall-cmd`` (:issue:`7900`)
 
 - Commands that wrap ``cd`` (using ``complete --wraps cd``) get the same completions as ``cd`` (:issue:`4693`).
+- Completion defined with ``complete -p`` now also work when the commandline uses a relative path to the command (:issue:`6001`).
 
 Improved terminal support
 ^^^^^^^^^^^^^^^^^^^^^^^^^

src/complete.cpp

@@ -573,9 +573,13 @@ void complete_remove_all(const wcstring &cmd, bool cmd_is_path) {
 /// Find the full path and commandname from a command string 'str'.
 static void parse_cmd_string(const wcstring &str, wcstring *path, wcstring *cmd,
                              const environment_t &vars) {
-    if (!path_get_path(str, path, vars)) {
-        /// Use the empty string as the 'path' for commands that can not be found.
-        path->clear();
+    bool found = path_get_path(str, path, vars);
+    // If the command was not found, 'path' is the empty string.
+    // Resolve commands that use relative paths because we compare full paths with "complete -p".
+    if (found && !str.empty() && str.at(0) != L'/') {
+        if (auto full_path = wrealpath(*path)) {
+            path->assign(full_path.acquire());
+        }
     }
 
     // Make sure the path is not included in the command.

src/path.h

@@ -41,11 +41,11 @@ int path_get_config_is_remote();
 class env_stack_t;
 void path_emit_config_directory_messages(env_stack_t &vars);
 
-/// Finds the full path of an executable.
+/// Finds the path of an executable.
 ///
 /// Args:
 /// cmd - The name of the executable.
-/// output_or_NULL - If non-NULL, store the full path.
+/// output_or_NULL - If non-NULL, store the path.
 /// vars - The environment variables to use
 ///
 /// Returns:

tests/checks/complete.fish

@@ -396,3 +396,30 @@ complete -C'fudge eat yummyin'
 cd -
 
 rm -r $dir
+
+set -l dir (mktemp -d)
+cd $dir
+cd -
+
+: >command-not-in-path
+chmod +x command-not-in-path
+complete -p $PWD/command-not-in-path -xa relative-path
+complete -C './command-not-in-path '
+# CHECK: relative-path
+
+# Non-canonical command path
+mkdir -p subdir
+: >subdir/command-in-subdir
+chmod +x subdir/command-in-subdir
+complete -p "$PWD/subdir/command-in-subdir" -xa custom-completions
+complete -C './subdir/../subdir/command-in-subdir '
+# CHECK: custom-completions
+
+# Relative $PATH
+begin
+    set -lx PATH subdir $PATH
+    complete -C 'command-in-subdir '
+    # CHECK: custom-completions
+end
+
+rm -r $dir